The U.S. Navy and Air Force are scheduling as many as 100 attack, reconnaissance, and support missions daily over Iraq, according to a U.S. military official.

The flights have averaged 90 a day since Aug. 9, including as many as 30 by Air Force refueling tankers, according to the official, who asked not to be identified discussing the data. The sorties are mostly, but not exclusively, over northern Iraq.

Since Aug. 8, U.S. aircraft have been attacking mortar positions, mobile artillery, convoy vehicles and armored personnel carriers under President Barack Obama's authorization for airstrikes against the militant Islamic State in Iraq and Syria (ISIS) to protect religious minorities and American personnel in Erbil, the seat of the Kurdistan Regional Government.

Army Lt. Gen. William Mayville, director of operations for the Joint Chiefs of Staff, cautioned today that airpower alone has its limits.

"We've had a very temporary effect, and we may have blunted some tactical decisions" by ISIS militants to move farther east toward Erbil, Mayville told reporters at a Pentagon briefing. The strikes haven't been extensive enough to contain the militants or reduce their capabilities, he said.

The United States has conducted 15 targeted airstrikes since Aug. 8, using a combination of Air Force Predator drones, F-16 and F-15E fighters, and Navy F/A-18s, Mayville said.

Kurdish military forces, known as peshmerga, have begun receiving small-arms ammunition directly from the United States instead of through the Iraqi government in Baghdad, because their needs have become "pretty substantial," he said. "We want to help them with that effort," he said of the Kurds.

The United States also has provided food and water to civilians trapped on a mountain near the town of Sinjar who've been threatened with slaughter if they return to their homes. The Defense Department has flown 14 successful missions over four nights, providing 16,000 gallons of water and 75,000 meals, Mayville said. Estimates of the number of civilians stranded on the mountain have ranged from thousands to tens of thousands, he said.

There are no plans to expand air operations beyond the limited mission of protecting U.S. personnel on the ground and aiding civilians facing a humanitarian crisis, Mayville said.

Most of the daily flights are for surveillance and on standby patrol to strike if suitable targets are identified. The technology being used against small, independent targets such as convoys reflects a decade's worth of war-fighting advances, said former Air Force Chief of Staff Gen. Norton Schwartz.

Progress "in targeting methodology and associated intelligence, surveillance, and reconnaissance capabilities have enabled precise engagement of small, tactical, and fleeting targets," Schwartz, now president of Business Executives For National Security, said in an email.

Advances include better sensors on drones and the targeting pods on tactical aircraft used for surveillance, he said, adding that there also are available archives of surveillance imagery, "which facilitates rapid target identification."

If needed, the Pentagon also could employ B-1B bombers stationed in the region that each are capable of carrying 80 satellite-guided bombs, said Mark Gunzinger, an air power analyst with the nonpartisan Center for Strategic and Budgetary Assessments in Washington.

"Used effectively," U.S. airpower might put militant forces "on the horns of a dilemma: Stay in one place too long and you could be attacked, or move and you will be seen and attacked," Gunzinger said.

Obama authorized the strikes after pleas from Kurdish leaders trying to blunt the advance of ISIS, the Sunni extremist group that's terrorized religious minorities, including the Yezidis trapped in the mountainous area.

Among the U.S. aircraft in the region are F/A-18s from Carrier Air Wing 8 on the USS George H.W. Bush in the Persian Gulf. There are about 65 strike and support aircraft on the carrier.

The Air Force has about 90 aircraft in the region capable of supporting air strikes, including F-15E fighter-bombers made by Boeing, F-22 and F-16 fighters from Lockheed Martin, armed drones from San Diego-based General Atomics, and B-1B bombers.

The Air Force has aircraft stationed at Al Udeid Air Base in Qatar and Ali Al Salem in Kuwait, as well as aerial tankers at Incirlik Air Base in Turkey, a NATO ally.

Among the ordnance dropped by Navy and Air Force pilots have been the AGM-65 Maverick air-to-ground missile and the newer GBU-54 smart bomb from Chicago-based Boeing. The GBU-54, which the Navy declared fully operational a year ago, can be aimed with an aircraft's laser designator or programmed with GPS coordinates.

The manned aircraft have been joined by MQ-1 Predator drones launching Hellfire laser-guided weapons.

The manned aircraft, with tanker refueling, "can stay in the area for hours, observe movements on the ground, accurately determine locations of enemy versus friendlies or civilians, and then rapidly engage as the situation requires," David Deptula, a retired three-star Air Force general who was in charge of service reconnaissance and surveillance, said in an emailed statement.